could be a spider problem, but worth checking every thing that could of been disturbed during engine swap, spider easy enough to bypass.

Does it do it on bumpy roads, turning, braking ect? More importantly what kind of boat??:)

Is it runing off at all any other clues you can give us?

got to agree sounds like valve prob. Tip for future : If it aint broke.......

with rear prop removed you are still running through IRD, probably need both parts, sorry to be the bearer of bad news.

Not easy to price, what all do you want done at the same time, no point in transfering old worn parts on to new chassis.

Not me, am just a boy. not old enough to remember just trying to learn things that the old folk talk about.:D

In a similar position as far as work goes, and don't want to disagree too much but before we get to sentimental we should mention: matrix o-rings blend motors rad arm bushes broken wires coil packs a/c condensers diesel tank pumps h/p pumps door latches to name a few of the common ones, but...

jack up by chassis, this will help removing prop from studs without removing from diff.

What age/model is your defender?

the bits at bottom are 12v outlet red+ black-, you would of had interior lights at some point I would think, is there door switches. check your switches for purple wires.

fairly sure there is one towards clutch pedal side as I recall, not on flat floor but just as it turns up.

one for the 12v out and one for interior lighting possibly. have seen them before think they would be factory fit.

you may need new fob, if you only have one might be worth your while getting another anyway.

1983 model, thought they had record player instead of karaoke machine, maybe a recall.:D

I am not 100% on this one but will look into it for you

check all pipes large and small inc vac pipes going to and from all turbo and egr units.

What is millage on your f/l? Hope not but it could be a dmf problem.

do you have an edc unit, is c/c not cotrolled from it? Not sure myself not a system that I have had to do much with as generally reliable or maybe just not used much up in N/S scotland, not enough motorways.

Did you put pics somewhere else or have you sussed it?